* Eric Prud'hommeaux <eric@w3.org> [2009-12-05 17:16-0500]
> I'll be working on this more, but here's a start on the slides
> introducing algebra for RDB->RDF and (corresponding) SPARQL->SQL
> mappings.
I broke the link on the wiki (pointed to my laptop).
http://www.w3.org/2009/Talks/1215-SWObjects-egp/
covers everything I want to tomorrow. I've covered
most of the algebra differences between SPARQL over
an SQL triples view and SPARQL over generic (e.g. 3FN)
relational data.
I know that a lot of this requires the narrative in
my head, but if anyone notices something conspicuously
absent by tomorrow's call, let me know.
> If folks want to play with this stuff, try downloading
> the appropriate SPARQL from
> http://sourceforge.net/projects/swobjects/files/
> and executing "SPARQL -s http://hr.example/DB/ -e
> "PREFIX emplP: <http://hr.example/DB/Employee#>
> SELECT ?empName ?managName
> WHERE { ?emp emplP:lastName ?empName .
> ?emp emplP:manager ?manager .
> ?manager emplP:lastName ?managName }"
>
> You should see:
>
> SELECT emp.lastName AS empName, manager.lastName AS managName
> FROM Employee AS emp
> INNER JOIN Employee AS manager ON manager.id=emp.manager
>
> which corresponds closely (modulo NULLs) to the results expected in
> http://www.w3.org/2008/07/MappingRules/StemMapping#bgp1
>
> The pitch is that this is a doable and useful task and that the world
> will buy us many beers for accomplishing this.
> --
> -ericP
--
-ericP